1. Field of the Invention
The present invention generally relates to substrate processing. More particularly, the present invention relates to chemical vapor deposition processing of gallium arsenide (GaAs) wafers.
2. Background of the Related Art
Gallium arsenide (GaAs) wafers or substrates are typically used for forming high speed telecommunication integrated circuits or devices. As compared to silicon substrates, GaAs substrates provide different material properties that present different challenges during material processing. For example, GaAs substrates are more insulative as semiconductor substrates than Silicon substrates. Also, GaAs substrates provides lower thermal conductivity than silicon substrates.
As interconnect and device features decrease below sub-quarter micron dimensions, high density plasma chemical vapor deposition (HDP-CVD) has proven to be one commercially acceptable method for forming films on substrates and filling sub-quarter micron features without voids. For processing of silicon substrates, HDP-CVD processes have typically provided satisfactory deposition film quality and met commercial efficiency/throughput requirements. However, typical HDP-CVD processing of GaAs substrates presents problems of wafer breakage and cracks or fractures of the deposited films on GaAs substrates. Furthermore, the quality of the deposited films have not satisfied commercial requirements. For example, films deposited on GaAs substrates generally have hazy appearance and do not provide sufficient reflectivity for other processes, such as photolithography, to be performed on the deposited film.
Therefore, there is a need for a method for processing GaAs wafers that reduces wafer breakage. There is also a need for a method for processing GaAs wafers that improves deposition film quality and reduces haze on processed wafers.
One aspect of the invention provides a method for processing GaAs wafers that reduces wafer breakage. Another aspect of the invention provides a method for processing GaAs wafers that improves deposition film quality and reduces haze on processed wafers.
One embodiment of the invention provides a method for processing a substrate comprising disposing the substrate on a substrate support member in a high density plasma chemical vapor deposition chamber, depositing a film onto a surface of the substrate, and after deposition of the film, flowing a heat transfer gas in one or more channels on a substrate support surface of the substrate support member.
Another embodiment, provides a method of processing a gallium arsenide substrate, comprising disposing the substrate on a substrate support member in a high density plasma chemical vapor deposition chamber; providing a substrate bias signal to the substrate support member; energizing an inductive plasma generator in order to couple plasma-sustaining energy into the high density plasma chemical vapor deposition chamber; and depositing a film onto a surface of the substrate in presence of a plasma. After deposition of the film, the substrate bias signal is reduced and the plasma is sustained with the energy provided by the inductive plasma generator. After reducing the substrate bias signal, a heat transfer gas is flowed in one or more channels on a substrate support surface of the substrate support member.
Still another embodiment provides a controller for a high density plasma chemical vapor deposition chamber, wherein the controller contains programming which, when executed, configures the controller to perform operations of processing a gallium arsenide substrate. The operations comprise, during a deposition cycle, providing power to a plasma generator, providing power to a substrate support member to produce a substrate bias signal, and flowing processing gases into the high density plasma chemical vapor deposition chamber. During a substrate cooling cycle following the deposition cycle, the controller is configured to reduce the power to the plasma generator while still maintaining a plasma, reduce the power to the substrate support member, and open a valve to allow a heat transfer gas to flow into at least one channel on a substrate support surface of the substrate support member.